Absolutely amazing sheath. Easily the best I have ever used.
The whole thing is quite modular. You can remove the plastic insert, heat it, and form it to the shape of your knife to enhance retention. The handle retention strap can also be adjusted to fit a variety of handle shapes,
The only drawback that I can think of is that the secure points on the backside are a bit small for some leg straps; if you want to add one, you'll either need to be able to remove and reattach the clasps on your strap, or you'll need a strap with a clasp that can squeeze through a 1.5" gap. Not much of a drawback, really.
Anyway, I highly recommend the combat master sheath.
Got the Combat Master (your first link) and the Survival (your second link).
Love them both. The Survival holds my Ratweiler and the Combat Master holds
whichever 5 to 7 inch blade I'm carrying that day.
I have a Leatherman Charge that fits into the pouch of either sheath, as well
as a DMT diamond bi-fold. Nice setup.
I've been toying with the idea of getting another of the small ones....just
because I like them
I have zero experience with SpecOps, but I bought 4 of the similar sheaths from Blackhawk over 2 years ago. I haven't sent one to a customer yet and have no intention of doing so unless someone specifically requests one......and even then, I will probably try to talk them out of it. I would heed the advice of the poster who told you to fit the kydex liner to your knife. My experience with the Blackhawks was that "one size fits all" means that the sheath fits all knives poorly. They rattled around a lot and the handle keeper strap allowed the knife to slip about 1/2-3/4 of an inch out of the sheath. Call me old fashioned, but for $35-45, I was buying standard Randall sized Sullivan leather sheaths before their shop burned down. I hope that the SpecOps stuff is better than the Blackhawk sheaths, but I am biased. Both sheaths are made out of two of my four least favorite materials, kydex and nylon. The other two are G10 and Micarta...lol
I have one (combat master)for my D2 Ka-Bar and its a little loose. I might have to heat up the plastic insert to secure it. The big sheath that I have said it should fit up to 8" blade. I like it and I would recommend it. For $34.00 I think its worth it.